1. Field of the Invention
The present invention relates a flow diffuser with an elongate discharge nozzle which can be used as a 90.degree. elbow in piping systems. In an alternative embodiment, the flow diffuser can be used in conjunction with a fire hydrant. The present flow diffuser facilitates better measurement because it promotes laminar flow.
2. Description of the Prior Art
In piping systems, orderly or streamlined flow is desirable. When a fluid passes through a conventional valve or a 90.degree. turn at a conventional elbow, the fluid flow becomes disorderly or turbulent. This turbulent fluid does not return to a streamlined or laminar flow for at least 40-50 pipe diameters downstream of an elbow. (Assuming that the downstream piping is axially aligned with the outlet of the valve or elbow and has the same inside diameter.)
Turbulence can be caused by a number of factors including, but not limited to, boundary layer separation, sometimes referred to as flow separation, vortices, pressure waves, and/or cavitation. Turbulence in pipe systems often causes noise, vibration, erosion and/or stress cracking. Reduction of turbulence is desirable in valves, at elbows, in piping systems generally, upstream of gas or liquid measurement and downstream of compressor stations.
Turbulence also causes a drop in fluid pressure. Each time a fluid flows through a valve or an elbow, there is an incremental drop in fluid pressure between the inlet and the outlet. In transmission pipelines, pressure drops are undesirable. If the fluid pressure drops low enough, additional pumping stations may be required. In any event, adding pressure to the fluid in the pipeline increases transportation costs. Because the elbow of the present invention reduces turbulence, it has less of a pressure drop when compared with conventional 90.degree. elbows.
Elbow induced turbulence has been recognized and addressed by a number of prior art designs including the vanes of U.S. Pat. No. 5,197,509 and U.S. Pat. No. 5,323,661 which are located upstream from an elbow. These vanes impart rotation to the fluid as it passes through the elbow to reduce downstream turbulence. Others have considered the deleterious effects of elbow induced turbulence and have included rotation vanes both upstream and downstream of an elbow as described in U.S. Pat. No. 5,529,084. These inventions seek to create non-turbulent or laminar flow after fluid passes through a conventional elbow.
The use of curved vanes to influence fluid flow for various reasons is not a new concept. In U.S. Pat. No. 1,570,907, a plurality of vanes were used in a locomotive to separate water from steam.
In some piping systems, granular or particulate material will quickly wear out a conventional elbow. One way to address this problem is by increasing the radius of curvature of the elbow to about 10 pipe diameters. However, this is not entirely an acceptable solution, especially in areas where space is at a premium. There have been many attempts to solve this erosion problem, including the use of inserts in the elbow, the insert being a disposable item intended to be replaced when it wears out. Examples of this type of replaceable insert in an elbow can be found in the following U.S. Pat. Nos. 1,357,259; 2,911,235; 3,942,684; and 5,590,916.
Other proposed solutions to this erosion problem include a circular pocket off the elbow. This pocket accumulates a certain quantity of the particulate material which serves as a pad to absorb the blow of the subsequent material to reduce the erosive effects thereof as shown in U.S. Pat. Nos. 4,387,914 and 5,060,984.
Conventional valves are also known to create turbulence and a pressure drop between the inlet and the outlet. Robert H. Welker, the inventor herein and the inventor of U.S. Pat. No. 5,730,416, has developed various approaches to deal with valve induced turbulence. In another patent, U.S. Pat. No. 5,769,388, Mr. Welker has developed a plurality of vanes and passageways in the valve to reduce turbulence. The apparatus shown in U.S. Pat. No. 5,769,388 has certain shortcomings because of the short discharge nozzle which tapered at an included angle of approximately 12.degree.. There is still a need to reduce turbulence in elbows, in valves and in piping systems in general.